Sintered polycrystalline cubic boron nitride material

Abstract

Polycrystalline cubic boron nitride, PCBN, material and methods of making PCBN. A method includes providing a matrix precursor powder comprising particles having an average particle size no greater than 250 nm, providing a cubic boron nitride, cBN, powder comprising particles of cBN having an average particle size of at least 0.2 intimately mixing the matrix precursor powder and the cBN powder, and sintering the intimately mixed powders at a temperature of at least 1100° C. and a pressure of at least 3.5 GPa to form the PCBN material comprising particles of cubic boron nitride, cBN dispersed in a matrix material.

The invention claimed is: 
     
       1. A method of making a polycrystalline cubic boron nitride, PCBN, material, the method comprising:
 providing a matrix precursor powder comprising particles having an average particle size no greater than 250 nm; 
 providing a cubic boron nitride, cBN, powder comprising particles of cBN having an average particle size of at least 0.2 μm; 
 intimately mixing the matrix precursor powder and the cBN powder; and 
 sintering the intimately mixed powders at a temperature of at least 1100° C. and a pressure of at least 3.5 GPa to form the PCBN material comprising particles of cubic boron nitride, cBN dispersed in a matrix material; 
 wherein the PCBN material does not include any of the following milling media materials: tungsten carbide, silicon carbide, zirconium oxide, and boron carbide; and 
 wherein the method does not involve any milling process comprising said milling media materials. 
 
     
     
       2. The method of making a polycrystalline cubic boron nitride, PCBN, material according to  claim 1 , further comprising providing a matrix precursor powder comprising particles having an average particle size no greater than 100 nm. 
     
     
       3. The method of making a PCBN material according to  claim 1 , wherein the step of intimately mixing the matrix powder and the cBN powder comprises:
 dispersing the matrix precursor powder and the cBN powder in a solvent; 
 mixing the solvent, matrix precursor powder and cBN powder using an ultrasonic mixer; and 
 removing the solvent to leave an intimately mixed powder of matrix precursor particles and cBN particles. 
 
     
     
       4. The method of making a PCBN material according to  claim 1 , wherein the step of intimately mixing the matrix precursor powder and the cBN powder comprises dry acoustic mixing. 
     
     
       5. The method of making a PCBN material according to  claim 1 , comprising providing cBN particles with an average size between 0.2 and 15 μm. 
     
     
       6. The method of making a PCBN material according to  claim 1 , comprising providing cBN particles with an average size greater than 1 μm. 
     
     
       7. The method of making a PCBN material according to  claim 1 , comprising providing cBN particles with an average size in a range of 5 μm to 10 μm. 
     
     
       8. The method of making a PCBN material according to  claim 1 , wherein the matrix material comprises materials selected from compounds of any of titanium and aluminium. 
     
     
       9. The method of making a PCBN material according to  claim 8 , wherein the matrix material comprises any of titanium carbonitride, titanium carbide, titanium nitride, titanium diboride, aluminium nitride and aluminium oxide.